An Item Response Theory Analysis of the Psychosis Screening Questionnaire in Ethiopia.

Journal: Early intervention in psychiatry

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Affiliated Institutions:  Department of Psychiatry, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia. Department of Social and Behavioral Sciences, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA. Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA.

Abstract summary 

Few psychosis screening instruments have been tested for use in Africa, yet appropriate tools can increase the detection of self-reported psychotic symptoms, improve the detection of psychosis and impact its prognosis.The construct validity and factor structure of Psychosis Screening Questionnaire (PSQ) were tested with confirmatory factor analysis (CFA) and item response theory (IRT) in a sample of 1928 Ethiopian adults without any history of psychosis. We tested a unidimensional model with and without an item on mania. For IRT, unidimensional latent structure one-parameter logistic (1PL) and two-parameter (2PL) logistic models were tested and compared for relative fit using a likelihood-ratio test.The prevalence of lifetime positive screens was 2.8% in an Ethiopian sample of adults from a general medical setting. A unidimensional model demonstrated good fit for the PSQ, (CFI = 0.993, TLI = 0.986 and RMSEA = 0.025). For IRT, a 2PL model was the best fitting one. IRT tests of item difficulty and discrimination parameters showed that paranoia had the highest discrimination and lowest difficulty ( ), likely to be endorsed at low levels of psychotic features. Thought insertion had the highest item difficulty ( ). Overall, the measure captures the psychosis construct at higher levels of the latent trait and may be suited for detecting moderate to severe levels of psychosis.The PSQ is found to have good construct validity in screening for psychosis among Ethiopian adults. Future studies may focus on the diagnostic validity of the PSQ comparing it with a structured clinical interview.

Authors & Co-authors:  Yared Mahlet M Kim Hannah H HH Ametaj Amantia A Alemayehu Melkam M Stevenson Anne A Milkias Barkot B Girma Engida E Gelaye Bizu B Teferra Solomon S

Study Outcome 

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Statistics
Citations :  Ali, G.‐C., G. Ryan, and M. J. De Silva. 2016. “Validated Screening Tools for Common Mental Disorders in Low and Middle Income Countries: A Systematic Review.” PLoS One 11, no. 6: e0156939. https://doi.org/10.1371/journal.pone.0156939.
Authors :  9
Identifiers
Doi : 10.1111/eip.13609
SSN : 1751-7893
Study Population
Male,Female
Mesh Terms
Other Terms
Ethiopia;Psychosis Screening Questionnaire;confirmatory factor analysis;construct validity;item response theory
Study Design
Study Approach
Country of Study
Ethiopia
Publication Country
Australia